Heat Exchange Responses to Anticholinergics

摘要

Among the drugs used for treatment of psychoses are those compounds which impart a degree of anticholinergic activity on eccrine sweat glands. This disrupts thermoregulation but the mechanism is not known. Atropine (used by the U.S. Army as a nerve agent antidote) reduces thermoregulatory sweating, causing intense heat storage leading to hyperpyrexia. Saline and atropine (2 mg im) were injected in 14 healthy male subjects before and after heat acclimation which each subject walked on a treadmill in a hot-dry environment and in a hot-which environment. Mean skin temperature, rectal temperature and heart rate were continuously observed. Skin evaporative heat loss was determined. Heat acclimation reduced effective temperature by some 2.5 when compared with the unacclimated state after atropine injection. Additionally, in 4 males the effects of atropine injection were evaluated during moderate cycle exercise in a temperature environment. Esophageal, rectal and skin temperatures and chest and forearm sweating were recorded. Forearm blood flow (venous occlusion plethysmography) was measured. The thermoregulatory disadvantage of inhibited sweating by atropine as partially compensated for by enhanced arm blood flow. Heat acclimation reduces the hazards of heatstroke caused by exercise in the heat with atropine injection. Such a model can be used to predict responses to other anticholinergic magnets and has potential relevance in understanding psychotropic drug related hyperthermia. Keywords: Thermoregulation; Atropine; Blood flow; and Fevers.